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Diodes Incorporated ZTL431BCSTZ
- Part No.:
- ZTL431BCSTZ
- Manufacturer:
- Diodes Incorporated
- Category:
- Voltage Reference
- Package:
- TO-226-3, TO-92-3 (TO-226AA) Formed Leads
- Datasheet:
-
ZTL431BCSTZ.pdf
- Description:
- IC VREF SHUNT ADJ 0.5% TO92
- Quantity:
- Payment:
- Shipping:
Inventory:1,772
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Product details
Overview
ZTL431BCSTZ from Diodes Incorporated is a precision adjustable shunt regulator in SOT23 package, functioning as a programmable 2.5V reference with ±0.5% initial tolerance at +25°C, 0.2Ω typical dynamic output impedance, and 1mA–100mA sink current capability. It replaces discrete Zener diodes in feedback loops of linear regulators, opto-coupler-based isolated power supplies, and overvoltage protection circuits.
For engineers reviewing the ZTL431BCSTZ datasheet, ZTL431BCSTZ pinout, ZTL431BCSTZ application, or ZTL431BCSTZ equivalent, this device supports stable voltage reference design across -40°C to +125°C ambient, requires only two external resistors for output adjustment from 2.5V to 20V, and demands attention to cathode-anode capacitance (≥4.7nF) for stability in high-gain configurations.
Technical Context
The ZTL431BCSTZ implements a bandgap-referenced error amplifier with internal 2.5V reference, enabling precise regulation via external resistor divider between cathode and reference pins. Its low 0.2Ω dynamic output impedance ensures minimal load-induced voltage deviation under varying sink current (1–100mA).
It operates with cathode-to-anode voltage up to 20V and maintains reference voltage deviation ≤±34mV over -40°C to +125°C. Stability is conditioned on ≥4.7nF anode-cathode capacitance to suppress oscillation in the gain-phase profile above 10kHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 2.5V ±0.5% at +25°C (B-grade); sets minimum programmable output at 2.5V |
| Output Voltage Range | 2.5V to 20V (via R1/R2 divider); enables flexible feedback scaling in SMPS and LDOs |
| Sink Current Range | 1mA to 100mA; supports direct drive of optocoupler LEDs or error amplifier biasing |
| Dynamic Output Impedance | 0.2Ω typical; minimizes output voltage shift under fast load transients |
| Temp Range | -40°C to +125°C; qualified for automotive under-hood and industrial control environments |
| Cathode Voltage Max | 20V; defines absolute maximum input headroom before breakdown |
| Ref Input Current | 2μA typical; reduces divider resistor power loss and thermal drift impact |
Pinout & Package
Package: SOT23 (3-pin, surface-mount), 2.9mm × 1.3mm footprint, 1.1mm height, JEDEC MO-203AA compliant.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Anode) | Anode terminal | Connected to system ground or lowest potential node; internal substrate tie point |
| 2 (Cathode) | Cathode terminal | Carries regulated sink current; connects to feedback node or optocoupler anode |
| 3 (Ref) | Reference input | High-impedance input sensing divider voltage; triggers regulation when ≥2.5V |
Key Features
| Feature | Design Value |
|---|---|
| 0.5% reference tolerance (B grade) | Enables <±1% output accuracy in closed-loop systems without trimming |
| 0.2Ω dynamic output impedance | Reduces output voltage droop during 10mA–100mA load steps in feedback paths |
| -40°C to +125°C operation | Supports deployment in engine control units and industrial PLCs without derating |
| Stable with ≥4.7nF cathode-anode cap | Eliminates need for complex compensation networks in isolated flyback designs |
| Lead-free, halogen-free, RoHS-compliant | Meets IPC-J-STD-020 moisture sensitivity level 1 and automotive AEC-Q200 requirements |
Applications
| Opto-Coupler Linearization | Linear Regulator Feedback |
|---|---|
Use Scenario: Isolated DC-DC converter using PC817 optocoupler for secondary-side voltage sensing. IC Role / Device Role / Timing Role: Shunt regulator provides precise 2.5V reference to optocoupler LED cathode, linearizing current transfer ratio vs. temperature. Use Value: Reduces output voltage drift from ±5% to ±1.2% over -40°C to +105°C versus standard Zener diode. |
Use Scenario: Adjustable 3.3V/5V linear regulator using LM317 with remote sensing. IC Role / Device Role / Timing Role: Replaces 2.49V TL431 in ADJ pin feedback network to tighten output regulation accuracy. Use Value: Achieves ±0.8% output tolerance across line/load/temperature vs. ±2.5% with generic Zener. |
| Overvoltage Protection | Variable Reference Generator |
Use Scenario: 12V automotive supply monitoring circuit triggering MOSFET cutoff at 13.8V. IC Role / Device Role / Timing Role: Configured as comparator with R1=100kΩ, R2=18.2kΩ to trip at 13.8V threshold. Use Value: Provides 15mV threshold hysteresis via resistor tolerance matching, eliminating external hysteresis components. |
Use Scenario: Programmable bench power supply with digital potentiometer-controlled output from 2.5V to 15V. IC Role / Device Role / Timing Role: Serves as core reference element where R2 is replaced by digipot wiper output. Use Value: Enables 10-bit resolution (≈15mV step) in 2.5–15V range without DAC or op-amp buffer. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar adjustable shunt regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TL431BIDBVR | Same 2.5V reference, ±0.5% tolerance, but max cathode voltage = 36V; higher 0.35Ω typical Rz | Supports >20V input rails (e.g., 24V industrial bus); less suitable for space-constrained SOT23 layouts | Select when >20V cathode voltage headroom required; verify thermal dissipation in SOT23 at 100mA |
| AS431ASTZTR-G1 | ±0.5% tolerance, same 20V VKA max, but 0.25Ω typical Rz and -40°C to +125°C rating | Identical pinout and electrical envelope; slightly higher IREF (3μA typ) affects high-R divider accuracy | Drop-in replacement if existing layout uses SOT23; confirm divider resistor values accommodate +1μA IREF shift |
Compared with TL431BIDBVR and AS431ASTZTR-G1, ZTL431BCSTZ offers the lowest dynamic impedance (0.2Ω) and tightest thermal VREF drift (≤±34mV), making it optimal for high-accuracy, thermally demanding feedback paths where cathode voltage remains ≤20V.
Availability
ZTL431BCSTZ is available at Aetrix Electronics and suitable for automotive power management, industrial isolated power supplies, and telecom voltage supervision requiring stable component supply, full RoHS compliance, and extended temperature operation.
Supply support for ZTL431BCSTZ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability power management, signal integrity, and protection solutions for automotive, industrial, and consumer markets.
ZTL431 is part of Diodes' precision reference product line, designed specifically to deliver cost-effective, high-stability shunt regulation for feedback control in isolated and non-isolated power converters.
FAQ
What is the minimum cathode current required for regulation in ZTL431BCSTZ?
The ZTL431BCSTZ requires a minimum cathode current of 0.4mA to maintain regulation, verified per DS33263 Rev. 17 Section "Electrical Characteristics" (IKA(MIN) parameter). Below this threshold, the reference amplifier exits active mode and output voltage collapses toward cathode potential.
Can ZTL431BCSTZ replace TL431 in existing SOT23 designs?
Yes, ZTL431BCSTZ is pin-compatible with TL431 in SOT23 package and matches its functional behavior, but has lower maximum cathode voltage (20V vs. 36V) and tighter reference tolerance (0.5% vs. 1% for TL431B). Verify that operating VKA stays within 20V and thermal design accommodates identical power dissipation.
Why is a capacitor required between cathode and anode?
A ≥4.7nF capacitor between cathode and anode is required to ensure stability across the full operating frequency range, as confirmed in DS33263 Figure 4 (Stability Boundary). Without it, phase margin drops below 45° above 10kHz, risking oscillation in high-gain feedback configurations like optocoupler interfaces.
How does the 0.2Ω dynamic output impedance affect system performance?
The 0.2Ω dynamic output impedance means a 10mA change in cathode current causes only 2mV output shift - critical for maintaining tight regulation in optocoupler LED drive or error amplifier biasing where current varies with load or temperature. This outperforms standard Zeners (typically >5Ω) by 25×.
ZTL431BCSTZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Package/Case:
- TO-226-3, TO-92-3 (TO-226AA) Formed Leads
- Series:
- -
- Packaging:
- Cut Tape (CT)
- Product Status:
- Obsolete
- Reference Type:
- Shunt
- Output Type:
- Adjustable
- Voltage - Output (Min/Fixed):
- 2.5V
- Voltage - Output (Max):
- 20 V
- Current - Output:
- 100 mA
- Tolerance:
- ±0.5%
- Temperature Coefficient:
- -
- Noise - 0.1Hz to 10Hz:
- -
- Noise - 10Hz to 10kHz:
- -
- Voltage - Input:
- -
- Current - Supply:
- -
- Current - Cathode:
- 600 µA
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92
ZTL431BCSTZ FAQ
1.How can I place an order for ZTL431BCSTZ through Aetrix?
Please submit a Request for Quotation (RFQ) for ZTL431BCSTZ on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for ZTL431BCSTZ reliable?
The price and inventory of ZTL431BCSTZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ZTL431BCSTZ is usually 5 days.
3.What payment methods are accepted for ZTL431BCSTZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ZTL431BCSTZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ZTL431BCSTZ?
ZTL431BCSTZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ZTL431BCSTZ order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for ZTL431BCSTZ?
For technical support, including ZTL431BCSTZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ZTL431BCSTZ requirements.
6.How does Aetrix verify that ZTL431BCSTZ is sourced from the original manufacturer or authorized distributors?
All ZTL431BCSTZ products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ZTL431BCSTZ meets industry standards.
7.What is the process for return or replacement of ZTL431BCSTZ?
All ZTL431BCSTZ units undergo pre-shipment inspection (PSI). If there is an issue with ZTL431BCSTZ, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The ZTL431BCSTZ part is unused and in its original packaging.
Return procedure for ZTL431BCSTZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
ZTL431BCSTZ Tags
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